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Artificial disc replacement offers shorter hospital stays than circumferential fusion
Disc replacement and fusion offer improvement, but TDR had less operative time, blood loss.
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Three- to 4-year results from a Texas investigation show that artificial disc replacement achieved better results than circumferential fusion in all parameters tested, including Visual Analog Scale, Oswestry and patient satisfaction scores.
"In summary, at our institution at 3 to 4 years, we saw improved VAS (Visual Analog Scale) and Oswestry results following surgery in both fusion and ProDisc (Synthes Spine) patients," Jack E. Zigler, MD, said. "We saw better improvement in all parameters as well as patient satisfaction in the ProDisc patients vs. their fusion controls. There were no differences in results between single- and two-level ProDisc patients. And the hospital stay was significantly shortened by artificial disc replacement." Zigler spoke at the North American Spine Society annual meeting.
Zigler presented the results from a single center in the multicenter ProDisc study, which started in October 2001. The 17-center study had one- and two-level arms.
Each arm was randomized 2-1 to 360° fusion, a circumferential, instrumented fusion with bilateral pedicle screws and autogenous iliac crest graft. Researchers performed the study at the Texas Back Institute.
The investigators enrolled 193 consecutive patients in the study. Thirty-five patients had fusions (17 one-level and 18 two-level) and 158 patients received artificial discs (95 one-level and 63 two-levels).
The artificial disc group also included continued access, nonrandomized patients and a few compassionate-use patients, Zigler said during his presentation. Three surgeons performed the operations during the 4 years that this report covered.
Minimum 1-year follow-up
All patients were prospectively gathered, Zigler said. One hundred-fourteen patients were randomized. All patients had a minimum of 1-year of follow-up. Forty patients had 3 to 4 years of follow-up, Zigler said. The study included 106 men and 87 women with a mean patient age of 41 years.
Mean operative time for fusion was 232 minutes vs. about 75 minutes for artificial disc replacement (P<.001).
"The mean operative times were significantly different, but that would not be unexpected, since the control was a 360° and the investigational arm was an anterior procedure alone," Zigler said during his talk.
There was more blood loss with the fusion technique — 200 cc vs. 81 cc with the artificial disc replacement. Zigler said the posterior approach to the fusion caused the blood loss.
On average, artificial disc patients left the hospital 1.2 days earlier than fusion patients, Zigler said. When Zigler and colleagues examined the VAS scores, they noted a significant postoperative improvement. The VAS scores either remained steady or improved slightly over the next 3 years.
"There was no statistical difference between the two groups in our sample, although the trends are fairly obvious to see," Zigler said.
A look at the Oswestry scores yielded similar results.
Both groups improved significantly postoperatively. That trend remained stable at each data point for both procedures, although artificial disc patients had better scores each time, he said.
The data only reached significance at 3 months.
High patient satisfaction rate
Both groups had a high mean patient satisfaction rate, with a statistically significant difference between the two groups favoring the artificial disc at 24 months.
"If we ask these patients if they would have surgery again, we can see that at each data point, the artificial disc patients responded favorably more than their fusion counterparts," Zigler said. "And we did achieve statistical significance at 6, 12, 24 and 36 months."
Overall patient satisfaction for artificial disc patients was 87% compared to 62% for fusion patients, Zigler said.
The FDA approved Prodisc in August for single-level use from L3-S1. Two-level use remains investigational, Zigler said.
For more information:
- Zigler JE, Sachs BL, Rashbaum RF, Ohnmeiss D. A prospective randomized study comparing ProDisc to fusion. #11. Presented at the North American Spine Society 21st Annual Meeting. Sept. 26-30, 2006. Seattle.
- Jack E. Zigler, MD, clinical associate professor, the department of orthopedic surgery, University of Texas Southwestern Medical Center, Dallas, and spine surgeon, Texas Back Institute, Plano, TX; 972-608-5037.